The overall goal of the proposed research is to develop a cell culture based model on the corneal epithelium which will serve as a reliable predictor of ocular irritancy/toxicity and minimize (or eliminate) the use of the very controversial Draize rabbit eye test. Phase I research demonstrated the feasibility of such an endeavor: corneal cells were successfully harvested, propagated, cryopreserved and subsequently differentiated into a cornea-like tissue whose toxicological behavior correlated (r=0.914) with the limited number of eye irritants (n=8) studied during Phase I. In addition, an economic evaluation of using such an in vitro system indicated that testing costs could be reduced by at least 2 fold versus whole animal Draize testing. Phase II research will attempt to optimize the culture system developed during Phase I. A more extensive study of monolayer culture propagation, differentiation conditions, and the differentiated tissue's characteristics will be performed. In addition, a much broader correlation of the in vitro and in vivo results will be attempted using a published data base of known ocular irritants. Finally, adaptation of the in vitro procedures to human and bovine derived corneal epithelial cells will be investigated. PROPOSED COMMERCIAL APPLICATION: The proposed corneal model will find application in safety assessment for a broad variety of consumer product companies with potential toxicity and eye irritation concerns. In addition, the model will be useful in studies involving ocular wound healing, eye pharmacological agents, and other areas of basic eye research.